Hard coating composition, hard coating film and flexible display window

Abstract

The hard coating composition according to an embodiment of the present invention comprises: a polymerizable compound comprising a (meth) acrylate compound; a first absorbent having a maximum absorbance in a wavelength range of 400 nm to 500 nm; and a second absorbent having a maximum absorbance in a wavelength range of 500 nm to 600 nm. By using the hard coating composition, it is possible to produce an optical hard coating film having improved mechanical characteristics and providing optical filter characteristics.

Description

Technical Field

[0001] The present invention relates to a hard coating composition, a hard coating film and a flexible display window, and more particularly to a hard coating composition comprising a film base resin and an additive, a hard coating film formed therefrom and a flexible display window comprising the hard coating film. Background Art

[0002] In recent years, image display devices such as liquid crystal display (LCD) devices and organic light emitting display (OLED) devices have been becoming thinner and more flexible. As a result, the image display devices are widely used in various smart devices characterized by portability, such as smart phones, tablet PCs, and various wearable devices.

[0003] In order to protect the image display device from the influence of external environment such as scratches, drop shock, external moisture, oil, etc., a window film such as a tempered glass material may be formed on the display panel.

[0004] Recently, hard coatings are being developed that achieve impact resistance comparable to that of tempered glass while also improving flexibility to achieve flexible characteristics. In addition, in order to achieve optical characteristics such as color characteristics in thinner image display devices, it is necessary to design the material and composition of the hard coating.

[0005] For example, Korean Patent Publication No. 2016-0100121 discloses a hard coating composition including a mixture of (meth)acrylate monomers and a hard coating film using the same. Summary of the invention

[0006] Technical issues

[0007] An object of the present invention is to provide a hard coating composition having improved optical and mechanical properties.

[0008] An object of the present invention is to provide a hard coating film having improved optical and mechanical properties.

[0009] An object of the present invention is to provide a flexible display window including a hard coating film having improved optical and mechanical properties.

[0010] Solution to the problem

[0011] 1. A hard coating composition comprising: a polymerizable compound comprising a (meth)acrylate compound; a first absorbent having a maximum absorbance in a wavelength range of 400 nm to 500 nm; and a second absorbent having a maximum absorbance in a wavelength range of 500 nm to 600 nm.

[0012] 2. The hard coating composition according to 1 above, wherein the polymerizable compound comprises a polyfunctional (meth)acrylate and a urethane (meth)acrylate compound.

[0013] 3. The hard coating composition according to item 1 above, wherein the content of each of the first absorbent and the second absorbent is 0.001 parts by weight or more and less than 2 parts by weight based on 100 parts by weight of the hard coating composition.

[0014] 4. The hard coating composition according to item 1 above, wherein the content of each of the first absorbent and the second absorbent is 0.005 parts by weight or more and less than 1 part by weight based on 100 parts by weight of the hard coating composition.

[0015] 5. In the hard coating composition described in 1 above, a mixing weight ratio of the first absorbent to the second absorbent is 4:6 to 6:4.

[0016] 6. The hard coating composition as described in 1 above, further comprising a photoinitiator and an anti-fingerprint agent, wherein the anti-fingerprint agent comprises an organic silicon-based anti-fingerprint agent, a fluorine-based anti-fingerprint agent or a silicon-fluorine-containing anti-fingerprint agent.

[0017] 7. A hard coating film comprising a substrate layer and a hard coating layer, wherein the hard coating layer is formed on the substrate layer and is formed from the hard coating composition of the above embodiment.

[0018] 8. The hard coating film according to item 7 above, which is used as an optical filter of an image display device.

[0019] 9. The hard coating film as described in 8 above, which has light absorption characteristics in the wavelength range of 400 nm to 600 nm.

[0020] 10. The hard coating film as described in 9 above, which is used for an optical filter without a polarizing plate.

[0021] 11. A flexible display window, comprising a substrate layer and a hard coating layer, wherein the hard coating layer is formed on the substrate layer and is formed from the hard coating composition of the above embodiment.

[0022] Effects of the Invention

[0023] The hard coating composition of the exemplary embodiment of the present invention may include a polymerizable compound and a light absorber. The light absorber may have a maximum absorption wavelength in the range of 400nm to 600nm. Therefore, the hard coating film formed by the hard coating composition can provide the reflection prevention performance of the blue light and the green light of the image display device.

[0024] The hard coating film has improved scratch resistance and impact resistance, and can be used as a protective film or outer cover window of a flexible display. The hard coating film is applied to a thin flexible display without a polarizing plate, and can absorb or prevent the increase of blue light and green light reflected by the display panel due to the omission of the polarizing plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic cross-sectional view showing a hard coating film according to an exemplary embodiment.

[0026] Figure 2 is a schematic cross-sectional view showing a flexible display window and an image display device including the same according to an exemplary embodiment.

[0027] Figure 3 Graph showing transmittance of Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0028] Embodiments of the present invention provide a hard coating composition including a polymerizable compound and an absorbent. In addition, embodiments of the present invention provide a hard coating film, an optical filter, and a flexible display window manufactured using the hard coating composition.

[0029] The present invention will be described in more detail below with reference to the accompanying drawings and embodiments. However, the following drawings and embodiments attached and described in this specification are preferred embodiments of the present invention, and serve to further understand the technical concept of the present invention together with the above invention content, so the present invention should not be interpreted only in accordance with the matters recorded in these drawings and embodiments.

[0030] <Hard Coating Composition>

[0031] The hard coating composition of the exemplary embodiment may include a polymerizable compound and an absorbent.

[0032] The polymerizable compound may be a component of a substrate that undergoes photocuring to provide a hard coating. According to an exemplary embodiment, the polymerizable (meth)acrylate compound may be included. In the present application, "(meth)acrylate" is used as a term covering acrylates and methacrylates.

[0033] Non-limiting examples of the (meth)acrylate compounds include neopentyl glycol acrylate, 1,6-hexanediol (meth)acrylate, propylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolethane tri(meth)acrylate, 1,2,4-cyclohexane tetra(meth)acrylate, pentaglycerol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol tetra(meth)acrylate, and dipentaerythritol tri(meth)acrylate. dipentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, tripentaerythritol tri(meth)acrylate, tripentaerythritol hexatri(meth)acrylate, bis(2-hydroxyethyl)isocyanurate di(meth)acrylate, hydroxyethyl(meth)acrylate, hydroxypropyl(meth)acrylate, hydroxybutyl(meth)acrylate, isooctyl(meth)acrylate, isodecyl(meth)acrylate, stearyl(meth)acrylate, tetrahydrofurfuryl(meth)acrylate, phenoxyethyl(meth)acrylate, isobornyl(meth)acrylate, etc. These may be used alone or in combination of two or more.

[0034] In a preferred embodiment, the (meth)acrylate compound may include a multifunctional (meth)acrylate, thereby increasing the degree of curing of the hard coating layer to provide improved scratch resistance and impact resistance.

[0035] For example, the (meth)acrylate compound may include pentaerythritol tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, tripentaerythritol tri(meth)acrylate, tripentaerythritol hexatri(meth)acrylate, and the like.

[0036] In a preferred embodiment, the polymerizable compound or (meth)acrylate compound may further include a urethane (meth)acrylate compound, thereby increasing the elasticity and bending properties of the hard coating layer.

[0037] The above-mentioned urethane (meth)acrylate-based compound can be produced by reacting a hydroxyl-containing multifunctional (meth)acrylate with an isocyanate group-containing compound in the presence of a catalyst. Examples of the above-mentioned hydroxyl-containing multifunctional (meth)acrylate include 2-hydroxyethyl (meth)acrylate, 2-hydroxyisopropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, caprolactone ring-opening hydroxy acrylate, pentaerythritol tri / tetra(meth)acrylate mixture, and dipentaerythritol penta / hexa(meth)acrylate mixture.

[0038] Non-limiting examples of the isocyanate group-containing compound include compounds derived from 1,4-diisocyanatobutane, 1,6-diisocyanatohexane, 1,8-diisocyanatooctane, 1,12-diisocyanatododecane, 1,5-diisocyanato-2-methylpentane, trimethyl-1,6-diisocyanatohexane, 1,3-bis(isocyanatomethyl)cyclohexane, trans-1,4-cyclohexyl diisocyanate, 4,4 '-methylenebis(cyclohexyl isocyanate), isophorone diisocyanate, toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, xylene-1,4-diisocyanate, tetramethylxylene-1,3-diisocyanate, 1-chloromethyl-2,4-diisocyanate, 4,4'-methylenebis(2,6-dimethylphenylisocyanate), 4,4'-oxybis(phenylisocyanate), trifunctional isocyanates of hexamethylene diisocyanate, and trimethylolpropane addition toluene diisocyanate, etc.

[0039] In some embodiments, the content of the polymerizable compound may be about 20 to 60 parts by weight based on 100 parts by weight of the hard coating composition. When the content of the photopolymerizable compound is less than 20 parts by weight, it may be difficult to ensure sufficient hardness of the hard coating layer. When the content of the photopolymerizable compound is greater than 60 parts by weight, curling may occur in the hard coating layer, and the flexibility may be hindered.

[0040] In some embodiments, the polymerizable compound may include the multifunctional (meth)acrylate and the carbamate (meth)acrylate compound. The content of the multifunctional (meth)acrylate may be 10 to 30 parts by weight, and the content of the carbamate (meth)acrylate compound may be 10 to 30 parts by weight. Within the above range, the balance between the surface strength and the flexibility of the hard coating layer can be easily achieved.

[0041] According to an exemplary embodiment, the hard coating composition may include an absorbent having a maximum absorbance or a maximum absorption wavelength in a wavelength range of 400 nm to 600 nm. For example, a dye-based compound having a maximum absorbance in the wavelength range may be used as the absorbent.

[0042] Thus, a hard coating film or a window film including the hard coating layer can be provided as an optical filter having an enhanced anti-reflection function or color correction function for light with a wavelength in the range of 400 nm to 600 nm. Thus, a hard coating film or a display window having both mechanical properties such as impact resistance, scratch resistance, and fingerprint resistance and optical properties such as color correction can be realized.

[0043] In some embodiments, the content of the absorbent in the total 100 parts by weight of the hard coating composition may be 0.002 parts by weight or more and less than 4 parts by weight. When the content of the absorbent is less than 0.002 parts by weight, the color correction function may not be fully realized. When the content of the absorbent is 4 parts by weight or more, the transmittance and curing degree of the hard coating layer or hard coating film may be reduced.

[0044] In a preferred embodiment, the absorbent may include a first absorbent having a maximum absorbance in a wavelength range of 400 nm to 500 nm and a second absorbent having a maximum absorbance in a wavelength range of 500 nm to 600 nm.

[0045] As non-limiting examples of the above-mentioned first absorbent, there can be cited: FDB series (400-500nm absorption dyes) of Yamada Chemical Co., Ltd. (for example, FDB-009, FDB-001, FDB-002, FDB-003, FDB-004, FDB-005, FDB-006, FDB-007, etc.); Epolight series of Epolin Co., Ltd. (for example, Epolight 5820, Epolight 5663, Epolight5851, Epolight 7830, Epolight 5852, Epolight 5853, Epolight 5854, Epolight 5010, Epolight 5843, Epolight 7829, Epolight 5675, Epolight 5841, etc.); ADA series of HWSand Co., Ltd. (for example, ADA7644, ADA9876, etc.); QCR Solutions company's VIS series (for example, VIS404A, VIS423A, VIS433A, VIS435A, VIS441A, VIS461B, VIS465A, VIS486C, VIS494B, etc.). They can be used alone or in combination of two or more.

[0046] As non-limiting examples of the above-mentioned second absorber, there can be cited: FDG series (500-600nm absorption dyes) of Yamada Chemical Co., Ltd. (for example, FDG-001, FDG-002, FDG-003, FDG-004, FDG-005, FDG-006, FDG-007, etc.); Epolight series of Epolin Co., Ltd. (for example, Epolight5393, Epolight 5532, Epolight 5396, Epolight 5838, Epolight 5821, Epolight 5391, Epolight 5840, Epolight 5822, Epolight 5819, Epolight 5824, Epolight5699, Epolight 5397, etc.); ADA series of HWSand Co., Ltd. (for example, ADA5656, ADA8787, etc.); QCR Solutions company's VIS series (for example, VIS503A, VIS513A, VIS523A, VIS548B, VIS552A, VIS564B, VIS580A, VIS588C, VIS593A, etc.), etc. These may be included alone or in combination of two or more.

[0047] Since the first absorber and the second absorber described above are included, it is possible to easily ensure a balance between the anti-reflection and color correction functions for blue light and green light, respectively.

[0048] In some embodiments, the content of each of the first absorbent and the second absorbent in 100 parts by weight of the hard coating composition may be 0.001 parts by weight or more and less than 2 parts by weight.

[0049] Preferably, the content of each of the first absorbent and the second absorbent may be greater than 0.005 parts by weight and less than 1 part by weight, preferably 0.005 to 0.5 parts by weight, 0.005 to 0.1 parts by weight, or 0.01 to 0.1 parts by weight.

[0050] In some embodiments, the mixing weight ratio of the first absorbent to the second absorbent may be 4:6 to 6:4, preferably 4.5:5.5 to 5.5:4.5. Within the above ratio range, the absorption characteristics of the reflected light in the wavelength range of 400nm to 500nm and the reflected light in the wavelength range of 500nm to 600nm can be achieved in a balanced manner.

[0051] The hard coating composition of the exemplary embodiment may include a photoinitiator capable of forming free radicals by light irradiation. The photoinitiator may be used to polymerize the (meth)acrylate group included in the polymerizable compound to form an acrylic resin structure.

[0052] Examples of the photoinitiator include a type 1 initiator that generates free radicals by decomposing molecules due to differences in chemical structure or molecular bond energy, and a type 2 initiator that induces hydrogen decyclization by coexistence with a tertiary amine.

[0053] For example, the above-mentioned type 1 initiator can include: 4-phenoxydichloroacetophenone, 4-tert-butyldichloroacetophenone, 4-tert-butyltrichloroacetophenone, diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropane-1-one, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropane-1-one, 1-(4-dodecylphenyl)-2-hydroxy-2-methylpropane-1-one, 4-(2-hydroxyethoxy)-phenyl (2-hydroxy-2-propyl) ketone, 1-hydroxycyclohexyl phenyl ketone and other acetophenones; benzoin, benzoin methyl ether, benzoin ethyl ether, benzyl dimethyl ketal and other benzoin; phosphine oxides, titanocene compounds, etc.

[0054] For example, the type 2 initiator includes benzophenones such as benzoylbenzoic acid, benzoylbenzoic acid methyl ether, 4-phenylbenzophenone, hydroxybenzophenone, 4-benzoyl-4'-methyldiphenyl sulfide, and 3,3'-methyl-4-methoxybenzophenone; and thioxanthone compounds such as thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, and isopropylthioxanthone.

[0055] The above-mentioned photoinitiator may be used alone or in combination of two or more. In addition, the above-mentioned type 1 and type 2 initiators may be used alone or in combination.

[0056] For example, the photoinitiator may be about 0.1 to 10 parts by weight, preferably about 0.1 to 5 parts by weight, in a total of 100 parts by weight of the hard coating composition. When the content of the photoinitiator is less than 0.1 parts by weight, sufficient curing may not be performed to ensure the mechanical properties and adhesion of the hard coating film or hard coating. When the content of the photoinitiator is greater than about 10 parts by weight, poor adhesion, cracks, and curling may occur due to the curing shrinkage in the (meth)acrylate group.

[0057] In some embodiments, the hard coating composition may further include additives such as anti-fingerprint agents, antistatic agents, and leveling agents.

[0058] As the anti-fingerprint agent, a silicone-based anti-fingerprint agent, a fluorine-based anti-fingerprint agent, or a silicon-fluorine-based anti-fingerprint agent can be used.

[0059] The leveling agent may include silicone-based, fluorine-based, acrylic polymer-based agents and the like. Examples of commercially available leveling agents include BYK-307, BYK-323, BYK-331, BYK-333, BYK-337, BYK-373, BYK-375, BYK-377, BYK-378, and BYK-UV3570 from BYK Chemical Co.; TEGO Glide 410, TEGO Glide 411, TEGO Glide 415, TEGO Glide 420, TEGO Glide 432, TEGO Glide 435, TEGO Glide 440, TEGO Glide 450, TEGO Glide 455, TEGO Rad 2100, TEGO Rad 2200N, TEGO Rad 2250, TEGO Rad 2300, and TEGO Rad 2500 from 3M; and FC-4430 and FC-4432 from 3M.

[0060] Non-limiting examples of the antistatic agent include ionic liquids, conductive polymers, lithium salts, quaternary ammonium salts, and metal oxide particles.

[0061] In some embodiments, the hard coating composition may further include an ultraviolet stabilizer and / or a heat stabilizer as the additive. The ultraviolet stabilizer may prevent the surface of the coating film formed by the composition from being discolored or broken due to exposure to ultraviolet rays by blocking or absorbing ultraviolet rays.

[0062] UV stabilizers can be divided into absorbers, delustering agents (quenchers), hindered amine light stabilizers (HALS, Hindered Amine Light Stabilizer) according to their mechanism of action. For example, phenyl salicylate (Phenyl Salicylates, absorber), benzophenone (Benzophenone, absorber), benzotriazole (Benzotriazole, absorber), nickel derivatives (delustering agents), radical scavengers (Radical Scavenger), etc. can be used. As the above-mentioned heat stabilizer, polyphenol-based, phosphite-based and lactone-based heat stabilizers can be used.

[0063] The additives may be appropriately mixed and used at a level that does not interfere with the UV curing process and the hardness and optical properties of the hard coating layer. For example, the content of the additives may be in the range of about 0.1 to 5 parts by weight in 100 parts by weight of the hard coating composition.

[0064] In the hard coating composition of the embodiment of the present invention, a solvent commonly used in the technical field can be used without particular limitation.

[0065] For example, solvents such as alcohols (methanol, ethanol, isopropanol, butanol, methyl cellosolve, ethyl cellosolve, etc.), ketones (methyl ethyl ketone, methyl butyl ketone, methyl isobutyl ketone, diethyl ketone, dipropyl ketone, cyclohexanone, etc.), acetates (ethyl acetate, propyl acetate, n-butyl acetate, tert-butyl acetate, methyl cellosolve acetate, ethyl cellosolve acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, methoxybutyl acetate, methoxypentyl acetate, etc.), hydrocarbons (hexane, heptane, octane, etc.), benzenes (benzene, toluene, xylene, etc.), ethers (diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dipropyl ether, diethylene glycol dibutyl ether, propylene glycol monomethyl ether, etc.) can be used. These solvents can be used alone or in combination of two or more.

[0066] The content of the solvent is not particularly limited as long as it can dissolve the components of the composition, and can be the remainder other than the components and additives. For example, the content of the solvent can be about 20 to 70 parts by weight in 100 parts by weight of the hard coating composition.

[0067] When the content of the above solvent is less than 20 parts by weight, the viscosity of the composition may be excessively increased, and the coating type and operability may be reduced. When the content of the above solvent is more than 70 parts by weight, it may be difficult to form a hard coating film or hard coating layer with uniform thickness, and streaks may be generated during drying, thereby damaging the optical properties.

[0068] <Hard coating, optical filter>

[0069] Figure 1 is a schematic cross-sectional view showing a hard coating film according to an exemplary embodiment.

[0070] Reference Figure 1 The hard coating film may include a substrate layer 100 and a hard coating layer 110 formed on one side of the substrate layer 100 .

[0071] The substrate layer 100 may use a transparent polymer film to be applied to a flexible display. For example, the substrate layer 100 may include a polymer film such as triacetyl cellulose, acetyl cellulose butyrate, ethylene-vinyl acetate copolymer, propionyl cellulose, butyryl cellulose, acetyl propionyl cellulose, polyester, polystyrene, polyamide, polyetherimide, polyacrylic acid, polyimide, polyethersulfone, polysulfone, polyethylene, polypropylene, polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetal, polyetherketone, polyetheretherketone, polyethersulfone, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, etc. The substrate layer 100 may include one or more of them.

[0072] In a preferred embodiment, the substrate layer 100 may include a polyimide-based resin to ensure high elasticity that can be applied to a flexible display.

[0073] The hard coating layer 110 may be formed by applying the hard coating composition of the above exemplary embodiment on the substrate layer 100 and then performing a curing process such as an ultraviolet curing process. For example, the hard coating composition may be applied by a printing or coating process such as a slot coating method, a doctor blade coating method, a spin coating method, a casting method, a micro-gravure coating method, a gravure coating method, a rod coating method, a roller coating method, a wire bar coating method, a dip coating method, a spray coating method, a screen printing method, a gravure printing method, a flexographic printing method, an offset printing method, an inkjet coating method, a dispensing printing method, a nozzle coating method, a capillary coating method, and the like.

[0074] The hard coating layer 110 may contain the above-mentioned absorbent, thereby absorbing or blocking light in the range of 400 nm to 600 nm reflected by the display panel to provide anti-reflection properties.

[0075] In addition, the hard coating layer 110 provides an exposed surface visible or contactable to the user, and may include a resin material generated from the above-mentioned polymerizable compound, thereby having improved scratch resistance and flexibility.

[0076] In some embodiments, the hard coating layer 110 may be provided as an anti-fingerprint film by further comprising the anti-fingerprint agent, antistatic agent, etc.

[0077] In some embodiments, a protective film may be stacked on the hard coating layer 110. The protective film may be provided as a release film, for example, and may be combined with the hard coating layer 110 via an adhesive layer. When removing the protective film, the antistatic agent may be used to effectively reduce static electricity generation.

[0078] As described above, the hard coating film can be provided as an optical filter with improved anti-fingerprint and scratch resistance properties. The optical filter can be arranged on the front or outermost surface of a flexible display device and provided as an outer cover window of the display, and can function as a color correction film of the flexible display device.

[0079] In some embodiments, the optical filter may be formed of the hard coating film and may not include other optical layers such as a polarizing plate or a polarizer.

[0080] Thus, the flexibility can be improved by omitting the polarizing plate or polarizer. The increase in reflectivity in the wavelength range of 400nm to 600nm caused by omitting the polarizing plate or polarizer can be absorbed or blocked by the above-mentioned absorbent. Therefore, a thin optical filter that can achieve both flexibility and anti-reflection properties can be provided.

[0081] <Image display device and flexible display window>

[0082] Figure 2 is a schematic cross-sectional view showing a flexible display window and an image display device including the same according to an exemplary embodiment.

[0083] Reference Figure 2 , the image display device of the exemplary embodiment may include a display panel 300 and a flexible display window 200 stacked on the display panel 300 .

[0084] The display panel 300 may include a pixel electrode 310 , a pixel definition film 320 , a display layer 330 , a counter electrode 340 , and an encapsulation layer 350 disposed on a panel substrate 305 .

[0085] The panel substrate 305 may include a flexible resin such as polyimide, thereby providing the image display device as a flexible display.

[0086] A pixel circuit including a thin film transistor (TFT) may be formed on the panel substrate 305, and an insulating film may be formed to cover the pixel circuit. The pixel electrode 310 may be electrically connected to the drain of the TFT on the insulating film, for example.

[0087] The pixel definition film 320 may be formed on the insulating film to define the pixel region by exposing the pixel electrode 310. The display layer 330 may be formed on the pixel electrode 310, and the display layer 330 may include, for example, a liquid crystal layer or an organic light emitting layer.

[0088] According to an exemplary embodiment, the display layer 330 may include an organic light emitting layer, and the image display device may be a flexible organic light emitting diode (OLED) display.

[0089] The counter electrode 340 may be disposed on the pixel definition film 320 and the display layer 330. The counter electrode 340 may be provided as, for example, a common electrode or a cathode of the image display device. An encapsulation layer 350 for protecting the display panel 300 may be stacked on the counter electrode 340.

[0090] The flexible display window 200 including the hard coating film may be combined on the encapsulation layer 350 or the display panel 300 .

[0091] The flexible display window 200 may include a substrate layer 100 and a hard coating layer 110 formed of the hard coating composition. The substrate layer 100 may be disposed on one side of the display panel 300, and the hard coating layer 110 may be exposed on the user side.

[0092] According to an exemplary embodiment, the image display device may be a flexible display without a polarizing plate or a polarizer. Thus, the blue light and green light reflected by the display panel 300 may be blocked and absorbed by the hard coating layer 110 as described above.

[0093] Therefore, the flexibility characteristic and the folding characteristic may be improved by omitting the polarizing plate, and a flexible display having improved mechanical stability and color characteristics may be implemented through the flexible display window 200 .

[0094] Below, experimental examples including specific embodiments and comparative examples are provided to help understand the present invention, but this is only to illustrate the present invention and does not limit the scope of the appended claims. It is obvious to those skilled in the art that various changes and modifications can be made to the embodiments within the scope and technical concept of the present invention. Of course, such changes and modifications also fall within the scope of the appended claims.

[0095] Examples and Comparative Examples

[0096] Example 1

[0097] 20 parts by weight of pentaerythritol triacrylate, 20 parts by weight of 10-functional urethane acrylate (MIRAMER MU9500, manufactured by Miramer), 2 parts by weight of 4-hydroxycyclohexyl phenyl ketone (photoinitiator), 56.98 parts by weight of methyl ethyl ketone (MEK), and 1 part by weight of a fluorine-based additive (Optool DAC-HP, manufactured by Daikin Corporation) as an anti-fingerprint additive were uniformly mixed.

[0098] Then, 0.01 parts by weight of the first absorbent (Epolight 5843) and 0.01 parts by weight of the second absorbent (Epolight 5396) were mixed into the hard coating composition to prepare a total of 100 parts by weight of the hard coating composition.

[0099] The hard coating composition was coated on a PET film with a thickness of 65 μm, the solvent was dried, and then a high-pressure mercury lamp was used under nitrogen purge at 600 mJ / cm 2 The film was cured by applying light of an amount of 1000 nm, thereby forming a hard coating layer with a thickness of 5 μm.

[0100] Example 2

[0101] A hard coating film was produced by the same method as in Example 1 except that pentaerythritol triacrylate was changed to hexapentaerythritol triacrylate.

[0102] Example 3

[0103] A hard coating film was produced by the same method as in Example 1 except that the amounts of the first and second absorbers were each changed to 0.015 parts by weight and the amount of methyl ethyl ketone (MEK) was changed to 56.97 parts by weight.

[0104] Example 4

[0105] A hard coating film was produced by the same method as in Example 1 except that the amounts of the first and second absorbers were each changed to 1 part by weight and the amount of methyl ethyl ketone (MEK) was changed to 55 parts by weight.

[0106] Example 5

[0107] A hard coating film was produced by the same method as in Example 1 except that the amounts of the first and second absorbers were each changed to 2 parts by weight and the amount of methyl ethyl ketone (MEK) was changed to 53 parts by weight.

[0108] Comparative Example 1

[0109] A hard coating film was produced by the same method as in Example 1, except that the first and second absorbers were not added and the amount of methyl ethyl ketone (MEK) was increased to correspond to the amount of the omitted absorber.

[0110] Experimental example

[0111] The physical properties of the hard coating films of Examples and Comparative Examples were evaluated as follows.

[0112] (1) Determination of maximum absorbance (%) at 400-500 nm

[0113] Using a transmittance measuring device, an ultraviolet visible spectrophotometer (UV-vis spectrometer, UV-2600, Shimadzu Corporation), the maximum value of the difference between the transmittance of each example and the transmittance of Comparative Example 1 in the 400-500 nm region was calculated as the maximum absorbance (%) in the 400-500 nm range.

[0114] (2) Determination of maximum absorbance (%) at 500-600 nm

[0115] Using a transmittance measuring device, an ultraviolet visible spectrophotometer (UV-2600, Shimadzu Corporation), the maximum value of the difference between the transmittance of each example and the transmittance of Comparative Example 1 in the 500-600 nm region was calculated as the maximum absorbance (%) in the 500-600 nm range.

[0116] (3) Adhesion evaluation

[0117] The hard coat film was bonded to the glass with an adhesive with the hard coat surface facing upward, and then 11 lines were drawn in the horizontal and vertical directions at 1 mm intervals on the hard coat layer to form 100 squares, and then tape peeling was performed three times with Michelob tape.

[0118] Thereafter, the adhesion was evaluated according to the following criteria.

[0119] ○: No peeling in 100 squares

[0120] △: One or more and less than 10 out of 100 squares peeled off

[0121] ×: 10 or more squares peeled off out of 100 squares

[0122] (4) Scratch resistance evaluation

[0123] The hard coating film was bonded to the glass with the hard coating surface facing upward, and then steel wool (#0000) was used at a speed of 500 g / cm 2 The hard coating surface was rubbed back and forth 10 times with a load of . The scratch resistance was evaluated according to the following criteria.

[0124] ○: Fewer than 10 scratches

[0125] △: 10 to 20 scratches

[0126] ×: More than 20 scratches

[0127] (5) Contact angle measurement

[0128] The hard coat film was bonded to a glass with the hard coat surface facing upward, and then the water contact angle of the hard coat surface was measured using a contact angle meter DAS-100.

[0129] (6) Fingerprint resistance evaluation

[0130] The hard coat film was bonded to glass with an adhesive with the hard coat surface facing upward, and then the hard coat surface was rubbed back and forth 1,500 times with an industrial eraser (MINOAN) at a load of 500 g, and the water contact angle of the rubbed portion was measured. The anti-fingerprint property was evaluated according to the following criteria.

[0131] ○: Water contact angle of friction part is 95° or more

[0132] ×: Water contact angle at friction part is less than 95°

[0133] The evaluation results are shown in Table 1 below.

[0134] [Table 1]

[0135]

[0136] Referring to Table 1, in the embodiment including the first and second absorbers, absorption characteristics for light in the wavelength range of 400-600 nm are achieved. In the embodiment 4 and embodiment 5 where the amount of the absorber is slightly increased, the mechanical and physical characteristics that can be used as a flexible display window are slightly reduced.

[0137] Figure 3 Graph showing the transmittance of Example 1 and Comparative Example 1. Figure 3 In Example 1 including the absorber, the transmittance is reduced in the wavelength range of 400 nm to 600 nm, and the anti-reflection property in the wavelength range of 400 nm to 600 nm is achieved.

Claims

1. A hard coating composition comprising: A polymerizable compound comprising a (meth)acrylate compound; a first absorber having a maximum absorbance in a wavelength range of 400 nm to 500 nm; and The second absorber has a maximum absorbance in the wavelength range of 500 nm to 600 nm. 2 . The hard coating composition according to claim 1 , wherein the polymerizable compound comprises a polyfunctional (meth)acrylate and a urethane (meth)acrylate compound. 3 . The hard coating composition according to claim 1 , wherein the first absorbent and the second absorbent are each contained in an amount of 0.001 parts by weight or more and less than 2 parts by weight in 100 parts by weight of the hard coating composition. 4 . The hard coating composition according to claim 1 , wherein the content of each of the first absorbent and the second absorbent is 0.005 parts by weight or more and less than 1 part by weight in 100 parts by weight of the hard coating composition. 5 . The hard coating composition according to claim 1 , wherein a mixing weight ratio of the first absorbent to the second absorbent is 4:6 to 6:

4.

6. The hard coating composition according to claim 1, further comprising a photoinitiator and an anti-fingerprint agent, The anti-fingerprint agent includes an organic silicon-based anti-fingerprint agent, a fluorine-based anti-fingerprint agent or a silicon-fluorine-based anti-fingerprint agent.

7. A hard coating film comprising a substrate layer and a hard coating layer, The hard coating layer is formed on the base layer and is formed from the hard coating composition according to claim 1 . 8 . The hard coating film according to claim 7 , which is used as an optical filter of an image display device. 9 . The hard coating film according to claim 8 , which has light absorption characteristics in the wavelength range of 400 nm to 600 nm. 10 . The hard coating film according to claim 9 , which is used for an optical filter without a polarizing plate.

11. A flexible display window comprising a substrate layer and a hard coating layer, The hard coating layer is formed on the base layer and is formed from the hard coating composition according to claim 1 .

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